[GWP-ASan] Add missing dependency on C++ headers

[phosek]

Summary

GWP-ASan implementation uses standard C++ headers. When C++ library
is being built as part of the toolchain rather than relying on the
host one, we need to make sure that headers are in place before we
start building GWP-ASan otherwise the build will fail. This is the
same solution that's already used by other runtimes: ASan, HWASan,
libFuzzer and XRay.

[morehouse]

Seems reasonable to me if we're fine with using libc++. Mitch, did you intend to introduce the libc++ dependency include <ctime> here?

[hctim]

I've filed D62048 which should resolve the build order discrepancy. Would prefer to do that rather than this as GWP-ASan shouldn't need to clash swords with c++ standard library, as it shouldn't be using it in the first place :)

[phosek]

No longer needed since D62048 has landed.

compiler-rt/cmake/Modules/AddCompilerRT.cmake

 # add_compiler_rt_runtime(<name>
 #                         {OBJECT|STATIC|SHARED}
 #                         ARCHS <architectures>
 #                         OS <os list>
 #                         SOURCES <source files>
 #                         CFLAGS <compile flags>
 #                         LINK_FLAGS <linker flags>
 #                         DEFS <compile definitions>
+#                         DEPS <dependencies>
 #                         LINK_LIBS <linked libraries> (only for shared library)
 #                         OBJECT_LIBS <object libraries to use as sources>
 #                         PARENT_TARGET <convenience parent target>
 #                         ADDITIONAL_HEADERS <header files>)
 function(add_compiler_rt_runtime name type)
   if(NOT type MATCHES "^(OBJECT|STATIC|SHARED)$")
     message(FATAL_ERROR "type argument must be OBJECT, STATIC or SHARED")
     return()
   endif()
   cmake_parse_arguments(LIB
     ""
     "PARENT_TARGET"
-    "OS;ARCHS;SOURCES;CFLAGS;LINK_FLAGS;DEFS;LINK_LIBS;OBJECT_LIBS;ADDITIONAL_HEADERS"
+    "OS;ARCHS;SOURCES;CFLAGS;LINK_FLAGS;DEFS;DEPS;LINK_LIBS;OBJECT_LIBS;ADDITIONAL_HEADERS"
     ${ARGN})
   set(libnames)
   # Until we support this some other way, build compiler-rt runtime without LTO
   # to allow non-LTO projects to link with it.
   if(COMPILER_RT_HAS_FNO_LTO_FLAG)
     set(NO_LTO_FLAGS "-fno-lto")
   else()
     set(NO_LTO_FLAGS "")
if(type STREQUAL "OBJECT")
           DEPENDS ${sources_${libname}}
           COMMENT "Building C object ${output_file_${libname}}")
       add_custom_target(${libname} DEPENDS ${output_dir_${libname}}/${output_file_${libname}})
       install(FILES ${output_dir_${libname}}/${output_file_${libname}}
         DESTINATION ${install_dir_${libname}}
         ${COMPONENT_OPTION})
     else()
       add_library(${libname} ${type} ${sources_${libname}})
+      if(LIB_DEPS)
+        add_dependencies(${libname} ${LIB_DEPS})
+      endif()
       set_target_compile_flags(${libname} ${extra_cflags_${libname}})
       set_target_link_flags(${libname} ${extra_link_flags_${libname}})
       set_property(TARGET ${libname} APPEND PROPERTY
                    COMPILE_DEFINITIONS ${LIB_DEFS})
       set_target_output_directories(${libname} ${output_dir_${libname}})
       install(TARGETS ${libname}
         ARCHIVE DESTINATION ${install_dir_${libname}}
                 ${COMPONENT_OPTION}

compiler-rt/lib/gwp_asan/CMakeLists.txt

set(GWP_ASAN_HEADERS
   random.h
 )
 
 # Disable RTTI and exception support, as we want these libraries to be
 # C-compatible. Regular C source files can be linked against the generated
 # GwpAsan libraries using the Clang C compiler.
 set(GWP_ASAN_CFLAGS -fno-rtti -fno-exceptions)
 
+if (TARGET cxx-headers OR HAVE_LIBCXX)
+  set(GWP_ASAN_DEPS cxx-headers)
+endif()
+
 if (COMPILER_RT_HAS_GWP_ASAN)
   foreach(arch ${GWP_ASAN_SUPPORTED_ARCH})
     add_compiler_rt_runtime(
       clang_rt.gwp_asan
       STATIC
       ARCHS ${arch}
       SOURCES ${GWP_ASAN_SOURCES}
       ADDITIONAL_HEADERS ${GWP_ASAN_HEADERS}
       CFLAGS ${GWP_ASAN_CFLAGS}
+      DEPS ${GWP_ASAN_DEPS}
       PARENT_TARGET gwp_asan
     )
   endforeach()
 
   add_compiler_rt_object_libraries(RTGwpAsan
       ARCHS ${GWP_ASAN_SUPPORTED_ARCH}
       SOURCES ${GWP_ASAN_SOURCES}
       ADDITIONAL_HEADERS ${GWP_ASAN_HEADERS}
-      CFLAGS ${GWP_ASAN_CFLAGS})
+      CFLAGS ${GWP_ASAN_CFLAGS}
+      DEPS ${GWP_ASAN_DEPS})
 endif()